Category Archives: Water supply

Visualizing Colorado River challenges and options

The Colorado River, lifeblood of the Southwest, is in trouble. Demand for river water is rising as the region’s population continues to grow, but the Colorado’s inherently capricious supply is increasingly in doubt due to climate change.

A federal report released in December took an exhaustive look at the challenges facing the Colorado River Basin and it examined the options for dealing with expected shortages.  I’ve gone through the Colorado River Basin Water Supply and Demand Study and pulled out the key figures, which you can download at the bottom of this post.

Colorado River Bain Study from EcoWest on Vimeo.

Shortage projected

If I had to pick one graphic that summed up the dilemma facing the Colorado River, it would be this one:

Colorado River historical and projected water use and supply

Looking back in time, the graphic shows that water use in the basin steadily increased during the 20th century, but the river’s flow was predictably erratic (that blue line is a 10-year moving average but it’s still as uneven as the basin’s topography).

Looking ahead, water demand is expected to keep growing (the fuzzy areas indicate the uncertainty in the projections). Predicting the flow of the Colorado decades into the future is a tough task, but the study concluded that the supply would probably decrease, as indicated by the gentle downward slope of the blue line. By 2060, the imbalance between supply and demand is expected to be about 3.2 million acre-feet.

Comparing costs of solutions

Besides identifying the problem, the Basin Study evaluated a wide variety of proposals for addressing the shortfall—everything from increasing water conservation in cities and on farms, to building massive new pipelines and desalination plants, even far-fetched ideas like towing icebergs to Southern California.

I extracted data from a summary table in the study in order to visualize how these options compare, both in price and in how much water they’ll yield.

In the graphic below, I’ve ranked all of the options from highest to lowest cost (the unit here is dollars per acre-foot per year). I’ve also color-coded them by category.

Cost of options for Colorado River


As you can see, the range of costs is enormous, but there are some general patterns. Conservation measures are among the cheapest, while desalinating ocean water or covering reservoirs to reduce evaporation are pricey. (For a few of these options, the study provided a range of costs, but for simplicity’s sake I’ve used the average in this graphic.)

The chart below ranks the options by how much water they’re expected to yield in 2035.

Potential yield of options for Colorado River

Water conservation in agriculture and among municipal and industrial (M&I) users is projected to yield the most, but weather modification (aka cloud-seeding) also performs well on this measure.

I combined the cost and yield data into one graphic by varying the width of the bars by the volume of water that each strategy is expected to produce. The thicker the bar, the greater the yield. In this case, I used the projections for 2060, rather than 2035.

Cost and yield of options for Colorado River

In releasing the Basin Study in December, federal officials stressed the conservation options over massive new infrastructure projects, such as pumping the Missouri or Mississippi rivers to the Colorado Front Range. These graphics show why that’s pretty much a no-brainer: conservation delivers more bang for the buck and avoids the enormous environmental impacts of augmentation projects.


Download Slides: Colorado River Basin StudyDownload Slides: Colorado River Basin Study (4.61 MB pptx)
Download Notes: Colorado River Basin StudyDownload Notes: Colorado River Basin Study (1.55 MB pdf)
Download Data: Colorado River Basin StudyDownload Data: Colorado River Basin Study (26.92 kB xlsx)

Data sources

You can download the Basin Study and associated reports here.

The Denver Post had a good overview of the Basin Study’s release. See recent stories by the Los Angeles Times and Associated Press  for more on what the federal government is doing to follow up on the report.

EcoWest’s mission is to analyze, visualize, and share data on environmental trends in the North American West. Please subscribe to our RSS feed, opt-in for email updates, follow us on Twitter, or like us on Facebook.

Flow diagrams of U.S. and Western water use

Americans use an average of 410 billion gallons of water per day. Where does all that water come from and where does it go?

Flow diagrams from the Lawrence Livermore National Laboratory provide excellent summaries of the nation’s water use. These graphics, also known as Sankey diagrams, show how much we pump from groundwater aquifers, how many gallons of surface water we divert, and which economic sectors use the most water.

In this slide deck (download links at bottom of post), I’ve pulled together the flow diagrams for the 11 Western states, which show some interesting regional patterns in water use.

Flow diagrams of U.S. and Western water use from EcoWest on Vimeo.

Diagrams visualize commodity flows

Lawrence Livermore produces similar graphics for energy and carbon dioxide. In another post, I provide a little background on Sankey diagrams, which are a great tool for visualizing how a commodity flows through a system.

Data for the water diagrams come from the U.S. Geological Survey, which publishes a report every five years summarizing the nation’s water use (the latest year available is 2005).

The flow diagrams segment water sources into four main categories: fresh surface water, saline surface water, fresh groundwater, and saline (brackish) groundwater. Lawrence Livermore summarizes national-level water use this way:

Fresh surface-water, from lakes and rivers, is used at large scale in every sector of the economy. Saline surface water, primarily ocean water, is mostly used for once-through thermoelectric cooling, although some ocean water is used for industrial cooling and a small but growing amount of ocean water is being desalinated for public consumption. Significant quantities of fresh groundwater are used in irrigation and fresh groundwater plays an important role in both public supply as well as self-supplied domestic water consumption. Brackish groundwater is the most difficult water resource to use and is therefore primarily used in the mining sector and in power production (often in geothermal power plants).

Western states vary widely

The state-level slides reveal that water is managed very differently across the West, with some residents heavily dependent on surface water and others more reliant on groundwater. In Montana, Utah, and Wyoming, saline groundwater is an important source for mining and industry, while in Idaho and Oregon there’s a fair amount of fresh water devoted to aquaculture.

Across the region, the water delivered to homes and businesses is just a fraction of what’s devoted to growing crops. Consider the arid state of Arizona, where discussions about water tend to focus on the state’s growing cities. In reality, the graphic below (click to enlarge) shows that farming totally dominates water consumption in Arizona.

Arizona water flow

When examining these slides, it’s important to remember that the size of the rectangles and the connecting lines are not comparable from state to state. Instead, they show the proportions of surface water and groundwater that are directed to various uses within each state.

Lawrence Livermore also offers this caveat:

Water use data is notoriously hard to compile. Accounting policies vary between different water management districts and water use is not metered in the same way that higher-priced commodities are sold. Quantifying water use by location and sector requires substantial estimation.Water disposition is even more difficult to quantify. While the quality of wastewater discharge is measured regularly for environmental purposes, the total quantity of wastewater is not carefully monitored, especially when that wastewater already meets environmental regulations for discharge.

Despite these drawbacks, I’ve found these diagrams to be super-helpful in understanding Western and national water-use patterns. Once the U.S. Geological Survey releases data from the 2010 report, which isn’t expected until 2014, it’ll be interesting to see if there have been any significant shifts in water use.


Download Slides: Flow Diagrams for U.S. and Western water useDownload Slides: Flow Diagrams for U.S. and Western water use (11.44 MB pptx)
Download Notes: Flow Diagrams for U.S. and Western water useDownload Notes: Flow Diagrams for U.S. and Western water use (2.25 MB pdf)

EcoWest’s mission is to analyze, visualize, and share data on environmental trends in the North American West. Please subscribe to our RSS feed, opt-in for email updates, follow us on Twitter, or like us on Facebook.

Survey says: water bills are rising

In the West and around the nation, the price of water keeps going up.

Since 2010, Circle of Blue has been gathering water rate data in the 20 largest U.S. cities, plus 10 regionally representative cities. From 2011 to 2012, single-family residential water prices rose an average of 7.3 percent; since 2010, the increase is nearly 18 percent.

The graphics below show how water bills have changed in Western cities. One interesting feature of these charts is that they analyze water use under three different scenarios: low use (50 gallons per person daily), medium use (100 gallons per person daily), and high (150 gallons per person daily.) To promote conservation, many Western utilities have a progressive rate structure, which charges customers more per gallon if their use exceeds certain thresholds.

Mountain west water rates

Mountain Water PriceWest coast water rates WestCoastWaterPrice

On the national level, the price of water is rising at a pace much faster than the overall rate of inflation. The graphic below, from the Institute of Public Utilities at Michigan State University, compares the costs of various utilities and water/sewer bills really stand out.

Trends in utility prices

CPItrends Many Western utilities are searching for new (expensive) supplies to meet the rising demands of the growing customer base, putting upward pressure on rates. But the nation’s crumbling water works are perhaps an even bigger driver of the increasing costs, as Circle of Blue notes:

The upward trend for rates is an inherent feature of the water sector. Compared with other utilities, water departments require significantly more assets — pumps, pipes, and plants — to generate revenue. All of that hardware is expensive to maintain, and, as the fountain of water main breaks across the U.S. attests, a good portion of this infrastructure has come to the end of its effective life. The American Water Works Association recently estimated that replacing the nation’s pipes alone will cost $US 1 trillion over the next 25 years. Most of this will come from ratepayers, who pay as much as 99 percent of all money that is spent on water supply systems, according to the U.S. Conference of Mayors

Rising prices are generally portrayed as a bad thing in the media, and I’d just as soon spend my money on something other than my monthly water bill, but the bright side to increasing prices is that it can encourage more efficient water use.

For more on these issues, check out our water deck, which includes some slides on the price of water and the sorry state of our nation’s water infrastructure.

EcoWest’s mission is to analyze, visualize, and share data on environmental trends in the North American West. Please subscribe to our RSS feed, opt-in for email updates, follow us on Twitter, or like us on Facebook.